The species was originally named Agaricus traganus by Elias Magnus Fries in 1818.

[6] Fries' protologue (1818) was very brief, but it mentions the main characteristics of the species now considered to be C. traganus: fruity-smelling basidiomata, pileus pale lilac, stipe purplish-white and bulbous, flesh yellow.

Therefore, Liimatainen and colleagues designated a collection by Lindström from September 13, 1988, from a dry, sandy pine forest in Myran, Sweden, as the epitype due to the ambiguity of the material.

[7] Some authorities consider the American variant to be a distinct species, Cortinarius pyriodorus, reserving the name C. traganus for the European version.

[5] The cap is 4–13 cm (1+5⁄8–5+1⁄8 in) in diameter, initially spherical to convex, with the margin rolled inward, then flattened, sometimes with large, broad, central umbo.

It is vivid violet for a long time in the upper part above the cortina, paler below, and covered with a tough, whitish, boot-like veil, which usually leaves upright zones on the stem.

[11] Another lookalike species is Cortinarius muricinus with the cap either permanently violet or becoming rust-colored from the disc outward.

The gills are initially blue, dirty cinnamon when old, and the stem violet lilac, with lighter fragments of the veil later turning rust-colored.